Bump version to 0.12.0.rc2
Bump version to 0.12.0.rc2

shekibobo/mailboxer,lacco/mailboxer,WeConnect/mailboxer,jarkadlec/mailboxer,t27duck/mailboxer,mattherick/mailboxer,techstars/mailboxer,cantonyselim/mailboxer,jarkadlec/mailboxer,untitledstartup/mailboxer,roomaroom/mailboxer,shekibobo/mailboxer,chepri/mailboxer,Design-Collective/mailboxer,Design-Collective/mailboxer,untitledstartup/mailboxer,joshtate04/mailboxer,chepri/mailboxer,Groovej/mailboxer,modsaid/mailboxer,modsaid/mailboxer,joshtate04/mailboxer,cantonyselim/mailboxer,Groovej/mailboxer,netbrick/mailboxer,roomaroom/mailboxer,sai43/mailboxer,lacco/mailboxer,mailboxer/mailboxer,jason-wang-0401/mailboxer,t27duck/mailboxer,mattherick/mailboxer,jason-wang-0401/mailboxer,mailboxer/mailboxer,div/mailboxer,afalone/mailboxer,sai43/mailboxer,netbrick/mailboxer